A traditional bicycle wheel may include a rim formed of extruded metals or other materials that are bent and bonded into a circular shape having consistently shaped cross sections. Recently other materials, such as fiber reinforced plastics, have been used in the manufacture of bicycle rims, which may be formed into circular shapes through non-extrusion based processes.
Wheel rims generally may experience aerodynamic issues during use with a bicycle. For example, traditional cross-sectional shapes of bicycle wheel rims may cause a large amount of drag on the wheel when moving in a straight forward direction (i.e. zero degree wind yaw or approach angle), which will inhibit the forward motion of the bicycle. Also, the movement of surrounding air through the wheel when air approaches the wheel at an angle relative to the forward direction of the bicycle (i.e. non-zero degree or transverse wind yaw or approach angle) may cause a resultant transverse force on the wheel. If this force is applied at a location forward or rearward of the wheel steering axis, a moment about the steering axis of the bicycle may result. Airflow across bicycle rims at transverse angles is believed to result in a loss of attached flow around the wheel at certain wind yaw angles relative to a forward movement direction of the bicycle. The resultant transverse forces of this detached flow result in bicycle handling issues, as well as increased drag. The yaw angle at which flow around a wheel becomes detached is a stall point.
Reduction of zero yaw angle aerodynamic drag, as well as altering the stall point to reduce non-zero yaw angle aerodynamic drag and transverse forces that act on a wheel, can provide for a more controllable and better performing bicycle.